Roller shoulder bit



y 1 937. c. A. DEAN 2,080,117

ROLLER SHOULDER BIT (yaw/es ,4 060,2

Patented a] 11, 1937 I UNITED STATES PATENT OFFICE 2,080,117 ROLLERSHOULDER m Charles A. Dean, Bakersfield, Calif. Application August 1,1935, Serial No. 34,186

10 Claims.

'which as a whole is free-cutting and in which 10 cross-drag and wearare minimized; and further in which the working stresses are balanced sothat it is feasible to mount the cutters on roller or other low frictionbearings. An important purpose is to provide a bit that effectsrelatively rapid 15 initial penetration of a deflected side wall,followed by progressively increasing side thrusttoward the new cut sothat the bit will tend to dig itself in to the new wall.

A further object is to obtain improved arrangement and mounting ofcutters so as to steady a drill in operation and minimize deflection ofan established bore. further description herein of preferredembodivention comprises features of construction, combinations ofelements and arrangements of partswhich will be exemplified in theconstructions hereinafter described and of which the scope of 30application will be indicated in the appended claims.

In the drawing, which illustrates one preferred embodiment of thisinvention, Fig. 1 is a bottom or inverted plan view of the drill bit androller 35 cutter assemblyf Fig.- 2.is an elevation of the bit withcross-section through conoidal cross-roller cutters of the bit; and Fig.3 represents an elevation, partly in vertical section, of one of thelongitudinal cutters of the bit, viewed at a right angle 40 to Fig. 2along the plane 3-3.

This invention advantageously embodies a bithead in which are combinedcross-roller cutters of conoidal form, preferably, having upwardly andinwardly inclined cutting surfaces, and longitudi- 45 nal roller cuttershaving tangentially inclined side cutting surfaces and havingbottom-cutting teeth adapted to effect a leading 'cut into part of the,

bottom formation below the cross-roller cutters. This combinationpenetrates initially into a de- 50 flected wall in a wedge-likearrangement of cutting teeth and then advances with increasing cuttingeffect and side pull as the inclined longitudinal roller cutter isrotated against the bottom of the new cut. The rollers preferably aredis- 56 posed symmetrically in the bit to promote decutters 5 containbottom-cutting teeth H.

Other objects will appear with velopment and maintenance of astraightbore V hole.

Referring more particularly to the drawing, the bit-head comprises ashank I adapted for engagement with the usual rotary drill stem. Theshank 5 terminates in downwardly projecting arms 2 and 3 adapted tocarry roller cutters- These cutters comprise conoidal cross-rollercutter 4 and cylindrical longitudinal roller cutter 5. Longitudinal Thecross-rollencutters and the cylindrical longitudinal roller cuttersare'adapted to ream some portion of the side wall, but the cross-cutter.4 is adapted to function as leading cutter at the bottom edge and lowerpart of the side or periphery. as illustrated by the cut shown in Fig.3, while the' a cylindrical cutter 5 is adapted to function as leadingcutter at an inner portion of the bottom after a new out has beeninitiated. This arrangement facilitates initial penetration into theside of a deflected bore.

As shown in Fig. 2, cross-roller cutter 4 is mounted withroller-bearings 6 on spindle I and is locked thereto by screw [4.Spindle 1 projects inwardly from arm 2 and may be horizontal or may beinclined. The shape of roller 4 preferably is frustro-conical withinwardly and upwardly inclined bottom-cutting teethd. The base of roller4 faces outwardly of the bit, and is provided with teeth 9 adapted tooperate outwardly of the arms 2 and 3. Preferably this toothed portion 9of the base of cutter 4 intersects bottom teeth 8 at an acute angle, andthe cutter 4 is mounted so that thisedge'of intersection between teeth 8and 9 constitutes a wedge-like cutting element at the 5 periphery of thebore. This edge is to constitute the leading contact with the bore wall,as shown in Fig. 2 and shown also by the cut in Fig. 3. Teeth 9preferably cut the side of the bore substantially vertical, while teeth8 in combination 40 therewith tend to form a recess or a trough at thebottom edge, as illustrated in Fig. 3. Thus'when the drill is loweredinto a deflected bore hole and is rotated, cross-roller 4 tends readilyto embed itself in the lower wall, such as wall 1 0, and start avertical bore. As a shelf is cut into the deflected side, and the.cutters penetrate further, there is continual side thrustto work thedrill into ,the new bore. The bottom ,cutting teeth may be notched toaugment the side thrust.

The rotating drill penetrates thedefiected wall by continued chippingaction, effected initially by teeth 8 and 9 of the conoidalcross-rollers 4, and subsequently also by the bottom teeth 1 l onlongitudinal rollers 5. Low friction mounting of the roller cutters 4and 5 from arms 2 and 3 respectively, such as with ball bearings 6 ofcutter 4, tends to promote a multiplicity of chipping cuts rather than adragging action. As the bit is rotated in clockwise direction, theindividual teeth 8 and 9 of cross-rollers 4 are brought into action inopposite direction. These cutting teeth build up in the bore vwall theshoulder or shelf having an upward slope into which the cross-rollersgradually settle.

As the conoidal cross-rollers 4 sink into the defiected wall, thevertical edges of longitudinal roller cutters 5 take up a reaming actionalong the upper side wall of the new cut. Cutter 5, as

shown, is inclined tangentially with its top about 20 preferably in arearward direction from top to bottom having regard to the direction ofrotation. Thus cutter 5 is given a twist in its reaming cuts. Also bythis inclination of roller 5 its bottom cutter edges ll descend to alowermost point centrally of their forward edge. This is illustrated inFigs. 2 and 3. In Fig. 3 a vertical section through this cutter 5converges at tooth l2. The cutting elements of cutter 5 at theperipheral edge of the new drill hole are preferably above thecorresponding peripheral cut of the conoidal cross-rollers 4. Thus, asthe longitudinal roller cutter 5 comes into action to cut the bottom,the bottom conformation of the bore becomes that of an upward and inwardslope containing an arcute or dished out, deeper toward the center ofthe bore, as illustrated in Fig. 3.

The inclination and position of longitudinal cutter 5 serve to introducethis cutter gradually into the sloped bottom that is formed by conicalcutter 4. The bottom-cutting teeth of the longitudinal cutter 5 effect aleading cut into an inner part of the bottom formation below thecross-roller cutters 8, and in eifect thus become driven cutters, butmaximum penetration and cutting action of cutter 5 in this sloped bottomis thus attained gradually after the conoidal cutters 4 have initiated acut in the deflected side wall. The maximum bottom-cutting action ofcutter 5 occurs at the inner side of its individual axis, as illustratedin Fig. 3. Cutting resistance on the bottom of this longitudinal cutter,thus predominant at its inner periphery, rotates cutter 5 on itsindividual axis as the drill rotates, and thus accelerates the chippingaction of this longitudinal cutter both on the bottom and on the sidewall. As a result partly of the upward inclination of the new. bottomcut toward the center of the bit, combined with the delayed and gradualintroduction of the longitudinal cutter into the cut, the bit ratherthan being forced away from the cut is gradually drawn into the newshelf. After the bit has progressed into the deflected wall to a pointbeyond the center of the bit, the conformation of the cut is symmetricaland is of counterbalancing or stabilizing effecton both the bottom andsides of the bit,

This facilitates the use of low friction bearings and freedom ofrotation of the individual cutters. Consequently, as illustrated in thedrawing, the cutters tend to chip into the cleared portion of a cut. Theconoidal cutters tend to rotate counter to the rotation of the bit-headwhile the cylindrical longitudinal cutters by theprepon- 4 derance ofthrust ,at the inner portion of the bottom tend to rotate with thebit-head. Thus there results a variety of complemental chipping cutsover the surfaces of the new bore hole.

In accordance with the patent statutes, I have described what I nowregard as the preferred embodiment of this invention, and explained theprinciples thereof but within the terms of the appended claims-variousmodifications and adaptations of this invention may now become apparentto those skilled in the art.

What is claimed is;

1. A roller bit for earth drilling, comprising a head having incombination a cross-roller cutter mounted therein with bottom-cuttingteeth as a whole inclined upwardly and inwardly and extendingsubstantially to the axis of the head, and

a roller-cutter mounted therein for rotation about an axis longitudinalof the bit and having bottom-cutting teeth adapted to effect a leadingcut into the upwardly and inwardly inclined bottom formation left belowthe cut of the said up.- wardly inclined cross-roller teeth.

2. A roller bit for earth drilling, comprising a head having incombination a cross-roller cutter mounted therein with bottom-cuttingteeth as a whole inclined upwardly and inwardly and extendingsubstantially to the axis of the head, and a roller-cutter mountedtherein having bottomcutting teeth adapted to effect a leading cut intothe upwardly and inwardly inclined bottom formation left below the cutof the said upwardly inclined cross-roller teeth.

cutting teeth adapted to efiect a leading cut into the upwardly andinwardly inclined bottom formation left below the cut of the saidupwardly inclined cross-roller teeth.

4. A roller bit for earth drilling, comprising a head having incombination. a conoidal'crossroller mounted therein with bottom-cuttingteeth as a whole inclined upwardly and inwardly and adapted to effect aperipheral cut and to extend therefrom substantially to the axis of thehead, and a cylindrical roller-cutter mounted therein with its axislongitudinal of the bit and with its upper end forwardly inclinedsubstantially 20 in the direction of rotation of the drill and havingbottom-cutting teeth adapted to effect a leading cut into the upwardlyand inwardly inclined bottom formation left below the cut of the saidupwardly inclined cross-roller teeth.

5. A roller bit for earth drilling, comprising a head having incombination a conoidal crossroller cutter mounted therein withbottom-cutting teeth as a whole inclined upwardly and inwardly andhaving a base containing wall-cutting teeth making an acute angle withthe said bottom-cutting teeth, and a cylindrical roller-cutter mountedtherein with its axis longitudinal of the bit and its upper endforwardly inclined in the direction of rotation of the drill, thecylindrical roller having bottom-cutting teeth adapted to eflect aleading cut into the upwardly and inwardly inclined bottom formationleft below the cut of the said conoidal cross-roller bottom-cutter, andhaving longitudinal teeth adapted to ream the side wall above the areacontacted by. the side-cutting teeth of the conoidal crossroller.

6. A roller bit for earth drilling, comprising aosau'r roller cuttermounted therein with bottom-cut ting teeth as a whole inclined upwardlyand inwardly and adapted to effect a peripheral cut and to extendtherefrom substantially to the axis of the head and with'a basecontaining side-wall to effect a leading cut into the upwardly andinwardly inclined bottom formation left below the cut of the saidconoidal cross-roller bottom-cut- 'ter, and having longitudinal teethadapted to ream the side wall above the area contacted by theside-cutting teeth of the conoidal crossroller.

7. A ,roller bit for earth drilling comprising a head having incombination a conoidal crossroller mounted therein with bottom-cuttingteeth as a whole inclined upwardly and inwardly and extending from theperiphery substantially to the axis of the head, and a cylindricalrollercutter mounted therein with its axis longitudinal roller mountedtherein, with bottom-cutting teeth as a whole inclined upwardly andinwardly and extending from the periphery substantially to the axis ofthe head, and a cylindrical roller-cutter mounted therein with its axislongitudinal of the bit and from top to bottom rearwardly inclined inthe direction of rotation of the bit, and having bottom-cutting teethadapted to effect aleading cut into the upwardly and inwardly inclinedbottom formation left below the cut of the said conoidal cross-rollercutter, the bottomcutters of the conoidal cross-rollers at the outerperipheral edge of their out being adapted to effect a leading out belowthe corresponding outer edge of the cylindrical longitudinalroller-cutters.

9. A roller bit for earth drilling, comprising a head having a conoidalcross-roller cutter mounted therein with bottom cutting teeth as a wholeinclined upwardly and inwardly and with a base extended outwardly toclear the drill head, said base containing side wall-cutting teethintersecting said bottom-cutting teeth at an acute angle to .form awedge-like'peripheral cutting element adapted to facilitate penetrationof a deflected bore wall and a roller cutter mounted in the head toeffect a leading cut in the bottom formation above and inwardly of theperipheral cut of said acute-angled cutters.

10. A roller bit for earth drilling, comprising a head having incombination a conoidal crossroller cutter mounted therein withbottom-cutting teeth as a whole inclined upwardly and inwardly andextending substantially to the axis of the head-and with a base extendedoutwardly to clear the drill head, said base containing sidewall-cutting teeth intersecting said bottom-cutting teeth at an acuteangle to form a wedgelike peripheral cutting element adapted to faeilitate-penetration of a deflected bore wall and disposed to effect aleadingcut into the side of a deflected bore wall, the bithad havingtherein also a roller-cutter mounted for rotation about an axisgenerally longitudinal of the bit and containing bottom-cutting elementsadapted to effeet a leading cut into the upwardly and inwardly inclinedbottom formation left below the cut of the said conoidal cross-rollercutter.

CHARLES A. DEAN.

